In today's world of personal information and communications systems, the prevalence of portable information devices is rapidly growing, particularly systems built on the netbook, or sub-notebook, platform, as well as multifunctional communication devices known as smartphones or personal digital assistants (PDAs), Ultra-Mobile Personal Computers, (UMPC), or Mobile Internet Devices (MIDs), utilizing processors such as Atom or Moorestown CPUs manufactured by Intel, or running operating systems such as Symbian OS, Windows Mobile, and the like. Networks offering open access to the public, such as EDGE and 3G, and various WiFi networks (such as those based on the IEEE 801-type standards), have become commonplace and continue to grow in popularity.
As communication systems and devices grow in complexity and communications bandwidth, with data rates approaching tens of megabytes per second, the risk of users inadvertently obtaining malicious programs and other unwanted content also grows. Additionally, the increasing popularity of portable information devices and open networks creates ever-increasing opportunities for malicious actors, such as hackers, identity thieves, spammers, and the like, to victimize users of these technologies. The quantity and severity of threats to computer systems, such as viruses, worms, malware, spyware, hacker attacks, as well as unwanted content, such as phishing attacks and other spam, continue to grow.
Firewalls, antivirus, antispam, and other such security applications geared toward personal computers are well-known. However, applying known approaches to portable information devices presents special challenges. Designers of portable information device systems and software have a principal objective of producing a device that provides timely access to information from practically any point in any city of the world. Portable information devices must be affordable in the highly-competitive, low-margin present-day market. Further, portable information devices must offer the utmost in portability and usability, meaning small overall device size and sufficiently long times of operation (at least on the order of 24 hours). Performance and usability are often countervailing objectives with affordability and portability, since batteries account for a large portion of the device's overall size, weight and cost. Performance and usability are even countervailing objectives with one another, since increased processor clock speeds and memory correspond to increased energy demands.
All these requirements make it impractical to simply continually increase the processor power and data storage capacity by substantial amounts to provide improved portable information device security while maintaining performance, usability, portability, and cost attributes. These constraints, in turn, place limitations on the design of applications that run on portable information devices, especially security applications, which can require significant processor resources and memory capacity.
Therefore, effective security measures are needed that are particularly suited to meeting the unique needs of portable information devices.